Method of welding coil end of stator of electric rotating machine

Abstract

A method of welding a plurality of conductors to form a winding extending through an annular stator core. The conductors are inserted into slots formed in the stator core to have coil ends extending outside an end surface of the stator core. A plurality of pairs of the coil ends are arranged in diagonal arrays extending diagonally with respect to a radial direction of the stator core. The method inserts a first electrode into a gap between adjacent two of the diagonal arrays and then brings a second electrode close to one of the adjacent two of the diagonal arrays to arc-weld the pairs of the coil ends. This welding method enables the welding of the coil ends arrayed in the above layout efficiently while keeping the electrical insulation between the pairs of the coil ends.

What is claimed is: 
     
       1. A method of welding a plurality of conductors to form a winding extending through an annular stator core, the conductors being inserted into slots formed in the stator core to have coil ends extending outside one of opposed end surfaces of the stator core, a plurality of pairs of the coil ends being arranged in a circumferential direction of the stator core and also staggered in zigzag alignment in a circumferential direction of the stator core so as to form diagonal arrays of the pairs of the coil ends, each of the diagonal arrays extending diagonally with respect to the radial direction of the stator core, the method comprising:
 inserting a first electrode of a welding system into a gap between adjacent two of the diagonal arrays; and 
 bringing a second electrode close to one of the adjacent two of the diagonal arrays to weld the pairs of the coil ends, 
 wherein the pairs of the coil ends are arranged in the circumferential direction of the stator core in coaxial circular arrays, and the pairs of the coil ends of each of the coaxial circular arrays are disposed at regular intervals to have the diagonal arrays located at regular intervals away from each other in the circumferential direction of the stator core; and 
 wherein three or more pairs of the coil ends are also arranged in the radial direction of the stator core so that three or more radial arrays of the coil end pairs are respectively aligned to extend in the radial direction of the stator core. 
 
     
     
       2. A method as set forth in  claim 1 , wherein the first electrode is made of two discrete electrode strips, and one of the electrode strips is inserted into the gap from outside the stator core, while the other electrode strips is inserted into the gap from inside the stator core in alignment with the one of the electrode strips. 
     
     
       3. A method as set forth in  claim 1 , wherein the first electrode is made of two discrete electrode strips, and the two electrode strips are inserted into the gap so that they are disposed substantially parallel to each other. 
     
     
       4. A method as set forth in  claim 1 , wherein each of the diagonal arrays is curved at a given radius of curvature, and wherein the first electrode is curved at the given radius of curvature. 
     
     
       5. A method as set forth in  claim 1 , wherein each of the diagonal arrays extend straight, and wherein the first electrode extends straight. 
     
     
       6. A method as set forth in  claim 1 , wherein the first electrode has a width greater than those of the gaps, so that the first electrode is placed in contact with both adjacent two of the diagonal arrays. 
     
     
       7. A method as set forth in  claim 1 , wherein the first electrode is a negative electrode and the second electrode is a positive electrode. 
     
     
       8. A method as set forth in  claim 1 , wherein the second electrode is brought close to one of the adjacent two of the diagonal arrays to arc-weld the pairs of the coil ends. 
     
     
       9. A method as set forth in  claim 1 , wherein the first electrode is a bar having a circular or rectangular cross section.